Flavor Profile Analysis Research Articles

Development of a taste and odor expert system: present state, strengths, limitations and possible future evolution

This paper summarizes the development of an expert system designed to help solve taste and odor problems in drinking waters which cannot be attributed to typical odorous compounds such as geosmin or 2-methylisoborneol (MIB), but rather to complex mixtures of volatiles usually detected below their individual odor thresholds. Long-term studies at four different sites were carried out to create a data base including flavor profile analysis (FPA) and closed-loop stripping-gas chromatography (CLSA-GC-FID) data. Examination of the data using factorial correspondence analysis allowed us to establish statistical links between odor descriptors and specific volatile organics. A stochastic regression model was also built which permits estimation of a sample flavor profile from its chromatographic content. The strengths, limitations and possible future developments of this method are discussed in detail.

Extraction and identification of chemicals causing grassy odors in Flavor Profile Analysis (FPA) reference standards

The extraction and identification of natural fresh grass odor standard was studied. Fresh grass was allowed to sit in water until it released its grassy components to the water. The resulting grassy samples were analyzed and the chemicals responsible for the characteristic odors identified by Flavor Profile Analysis and sensory GC analysis. Closed-Loop Stripping Analysis was used for the isolation of volatile non-polar compounds and Simultaneous Distillation Extraction was used for the isolation of more polar chemicals of moderate volatility. A primary grassy odor standard (cis-3-hexenyl acetate) and a secondary grassy odor standard (cis-3-hexen-l-ol) were identified by Mass Spectroscopy and Sensory GC. Dose-Response curves were plotted and corresponding odor threshold concentrations (OTC) were determined for the cis-3-hexen-lol the cis-3-hexenyl acetate. It was found that cis-3-hexenyl acetate was approximately 50 times more odorous than the cis-3-hexen-l-ol. The OTC of cis-3-bexenyl acetate was found to be between 1 and 2 µg/l.

Oxidation of odorous and nonodorous algal metabolites by permanganate, chlorine, and chlorine dioxide

The six algal metabolites, at concentrations of 20-225 µg/l, were oxidized with potassium permanganate, chlorine, or chlorine dioxide at doses of 0.25-3 mg/l. Flavor profile analysis (FPA) was used to determine the odors of the solutions before and after oxidation. Linoleic and palmitic acids, which are odorless compounds, were oxidized to odorous products by all three oxidants. The odor intensity of β-cyclocitral (grape, sweet tobacco) and phenethyl alcohol (rose, floral) was only slightly decreased by any of the oxidants. Oxidation by permanganate or chlorine either eliminated or greatly reduced the odors associated with linolenic acid (watermelon) and 2t,6c-nonadienal (cucumber); chlorine dioxide was ineffective at reducing the cucumber odor of 2t,6c-nonadienal. Oxidation, at doses typically applied for drinking water treatment, can result in the destruction of certain algae-related odors but in the formation of other odors.

The determination of compounds causing fishy/swampy odors in drinking water supplies

Two chemical isolation methods, closed-loop stripping analysis (CLSA) and simultaneous distillation/extraction (SDE) in combination with gas chromatography/mass spectroscopy (GC/MS) and two sensory methods, flavor profile analysis (FPA) and sensory GC analysis, were used to determine the compounds responsible for the fishy/swampy odors in potable water. Samples were collected during four different fishy/swampy odor episodes and analyzed. It was determined that the compounds should be extracted by the SDE method. The SDE method extracts more polar compounds than the CLSA method. The main compounds identified were two unsaturated aldebydes (trans,trans-2-4-heptadienal and trans,4 heptenal). A ketone (1-penten-3-one) was tentatively identified.

The identification of odorous metabolites produced from algal monocultures

Four algal species commonly found in the River Seine were cultured for a comprehensive investigation of their odorous metabolites. Closed loop stripping analysis (CLSA), open stripping analysis (OSA) and steam distillation extraction (SDE) were used to extract and concentrate a wide range of metabolites. The odour causing compounds were identified by a combination of chemical (gas chromatography-mass spectrometry (GC-MS)) and sensory (sensory-gas chromatography (sensory-GC), flavour profile analysis (FPA)) analyses. The compounds found responsible for unpleasant odours were alkenes, saturated and unsaturated aliphatic alcohols, aldehydes, ketones, sulphides and pyrazines. Some of the odorous compounds responsible for septic and muddy/musty odours may have been of bacterial or fungal origin as the cultures were non-axenic. Sensory-GC was found to be a valuable tool in identifying compounds of very low odour thresholds, which were present at or below the detection limits of the GC-MS.

The influence of growth conditions on odor-compound production by two chrysophytes and two cyanobacteria

The influence of several environmental factors (e.g., light intensity, temperature, nitrogen, and phosphorus) on population density and odor-compound production of two ehrysophytes, Synura petersenii and Dinobryon cylindricum; and two cyanobacteria, Anabaena laxa and Phormidium calcicola was investigated. The odors associated with each alga were evaluated by flavor profile analysis (FPA) at several intervals during their initial culturing in defined media. Algal cell and media extracts were analyzed individually by capillary gas chromatography-mass spectrometry (GC-MS). Both cyanobacteria produced geosmin (“earthy” and “corn” odors); however, the P. calcicola also produced relatively large amounts of MIB (“musty-earthy” odors). Both chrysophyte cultures contained 2t,4c,7c-decatrienal (“fishy” odor); and in addition, 2t,6c-nonadienal (“cucumber” odor) was isolated from the S. petersenii.Young cultures of Anabaena laxa (e.g., <20 days) retained most of the geosmin produced. Throughout its population growth, more than 80 percent of the MIB and geosmin produced by P, calcicola was detected in the media rather than in the cells. Synura petersenii produced more 2t,4c,7c-decatrienal than 2t,6c-nonadienal and retained nearly 90 percent of both compounds throughout the algal population growth. Dinobryon cylindricum produced 2t,4c,7c-decatrienal, and, like the S. petersenii, retained most of the compound. Greater production of the compounds by the two chrysophytes was apparently associated with log-phase growth rather than specific environmental conditions; extended log-phase growth (and prolonged production of compounds) was observed in the S. petersenii culture during the low-temperature treatment.

Development of a taste and odor expert system: present state, strengths, limitations and possible future evolution

This paper summarizes the development of an expert system designed to help solve taste and odor problems in drinking waters which cannot be attributed to typical odorous compounds such as geosmin or 2-methylisoborneol (MIB), but rather to complex mixtures of volatiles usually detected below their individual odor thresholds. Long-term studies at four different sites were carried out to create a data base including flavor profile analysis (FPA) and closed-loop stripping-gas chromatography (CLSA-GC-FID) data. Examination of the data using factorial correspondence analysis allowed us to establish statistical links between odor descriptors and specific volatile organics. A stochastic regression model was also built which permits estimation of a sample flavor profile from its chromatographic content. The strengths, limitations and possible future developments of this method are discussed in detail.

The yield and quality of ginger produced by micropropagated plants as compared with conventionally propagated plants

SUMMARYMeristem-derived ‘Wynad local’ ginger plants were micropropagated in vitro. The performance of micropropagated plants (MP) in the field, as compared with conventionally grown plants (CP), was evaluated from rhizome yield and other quality factors. ‘Wynad local’ ginger is usually harvested after eight months and MP ginger rhizomes harvested at the same time werecomparable qualitatively and quantitatively to CP in the composition of starch, ash, acetone extract and volatile extract but only qualitatively similar in total oleoresin content, flavour profile, TLC aromagram and GC analysis, with less of each component than with CP ginger. The MP took two months longer cultivation to yield as much oleoresin and gingerols as inCP ginger. This difference was attributed to the fact that the micropropagated plants lacked a rhizome when planted and underwent shock during acclimatization. Periodic fluctuations in the yield and composition of various compounds are described.

Cucumber Flavor in Philadelphia's Drinking Water

Since 1981, when the use of free chlorine was curtailed to control trihalomethanes at the Baxter Treatment Plant in Philadelphia, Pa., a seasonal cucumber flavor problem occurred. Flavor profile analysis was the only tool available to guide treatment. During 1990, the cucumber odor was tracked more than 250 mi (402 km) up the Delaware River to the Cannonsville Reservoir, and the odor‐causing compound was identified as trans,2‐cis, 6‐nonadienal. Algae growth beneath the winter ice produced the compound. Other treatment plants on the river that used free chlorine for disinfection and a final residual never had a problem with trans,2‐cis,6‐nonadienal. Therefore, use of chlorine was increased at the Baxter plant to control the cucumber flavor. Studies were conducted on trans,2‐cis, 6‐nonadienal to describe its sensory characteristics and analytical detection limit.

Assessing the Quality of Flavor Profile Analysis Data

Flavor profile analysis (FPA) data for influent and effluent water samples from two Philadelphia treatment systems were studied, along with quality control protocols, in order to optimize the FPA method. The quality of the data was evaluated for (1) the qualitative description and (2) the quantitative response for each organoleptic descriptor.

A Comparison of 1988-1990 Flavor Profile Analysis Results with Water Conditions in Two Northern California Reservoirs

Flavor Profile Analysis (FPA) results were compared with water quality data for two storage reservoirs of the East Bay Municipal Utility District in Oakland, California to determine what conditions exist at the time of an earthy or musty taste and odor episode. Strong musty and earthy aromas coincided most frequently with fall Anabaena sp. blooms and summer Anacystis sp. blooms. Occasional Aphanizomenon sp. blooms were concurrent with Anabaena sp. blooms, so odor problems associated with Aphanizomenon sp. could not be distinguished. Geosmin concentrations of 30-140 ng/L were found in water containing 100,000-300,000 Anabaena sp. cells/100 mL, but 2-methylisoborneol concentrations never exceeded 25 ng/L. Both reservoirs experienced relatively odorless large spring diatom blooms resulting in high chlorophyll a concentrations, so chlorophyll a alone did not serve as a helpful indicator of imminent odor problems. Fall cyanobacteria blooms closely followed the onset of reservoir destratification, so weekly temperature and dissolved oxygen depth profiles successfully predicted the start of a cyanobacteria bloom. Musty and earthy odors in the filter plant effluent were lower than those in the influent, but effluent FPA numbers reached 4 during two large taste and odor episodes, suggesting that granular activated carbon installed 1-2 years earlier may not remove all odor-causing compounds of a large taste and odor episode.

Odor Standards in Squeeze-Bottle Kits for Matching Quality and Intensity

A valuable adjunct to flavor profile analysis, wastewater odor evaluation, and ambient air quality surveying is an array of reference odor standards for side-by-side comparisons with the unknown samples. Sets of convenient, nonspill squeeze-bottle standards have been developed for these purposes. Many of the required odor chemicals are stable in character up to six months in mineral-oil dilution and can provide hundreds of sniff-tests without significant loss of intensity. The author recently proposed a generalized “decismel scale” for describing odor threshold and odor level (by analogy with the decibel scale for sound). Prototype kits are suggested that demonstrate an odor intensity scale and a tentative selection of odor qualities.

Correlation of Chemical and Sensory Data by Principal Component Factor Analysis

The cause(s) of many taste and odor problems in drinking water remain unknown. If sufficient information about the problem is not available to develop a hypothesis, one can begin to develop a hypothesis to test by using correlation methods from data base information concerning the problem. This paper presents a method to develop a correlation between chemicals and sensory characteristics of.a set of water samples by Principal Component Factor Analysis. The correlations developed hypotheses for the causes of tastes and odors that must be further tested. A correlation indicates that a pattern is occurring between two data bases. In this case, the pattern is a change of a Chromatographie peak's detector response which parallels the sensory response of a flavor profile analysis panel for an organoleptic descriptor. The correlation must always be confirmed by sensory analysis. The results from an application of the method to data from the city of Philadelphia Water Department and Philadelphia Suburban Water Co. are shown. An evaluation of the results is described. The correlation between a sensory response and a chemical concentration in water was described by expanding the Weber-Fechner Law. The Weber-Fechner Law states that the odor intensity of a sensory descriptor is proportional to the logarithm of the concentration of the chemical associated with the odor. Two drinking water data sets from the Philadelphia Water Department and Philadelphia Suburban Water Co. were used to demonstrate the sensory-chemical correlation procedure. Correlations were observed. Clearly, a correlation indicates a possible relationship, a “presumptive result” that must be tested by sensory analysis to “confirm” if the relationship is true. A correlation indicates that a pattern is occurring between two data bases. In this case, the pattern is a change of a Chromatographie peak's detector response which parallels the sensory response of a flavor profile analysis panel for an organoleptic descriptor. The correlation must always be confirmed by sensory analysis as stated by the rules of scientific evidence.

Hochdruckextraktion von Majoran. 1. Mitt. Sensorische Charakterisierung von Majoranoleoresin mittels Profilanalyse

A flavour profile analysis has been developed for the evaluation of carbon dioxide extracts of marjoram. On the basis of the commercial quality of various proveniences of marjoram a first flavour profile was established. Components which decisively influence the flavour were examined for the determination of relevance factors. The taste profile is the basis for the calculation of the quality coefficient as measure of the sensory quality. The expert profile as a theoretical model is based on optimum intensities of individual taste components. Differences from the expert profile are considered by corrected intensities and lead to a decrease of the quality coefficient. The method used for the development of a high pressure extraction technology is quite suitable for the characterization of marjoram extracts as well as for the evaluation of commercial marjoram samples.

A critical review of methods used for the sensory evaluation of water quality

Presently, three methods of sensory evaluation are used by the water industry for the sensory evaluation of water quality. These are (1) the flavor threshold test, (2) the flavor rating scale, and (3) the flavor profile analysis. This article evaluates each sensory evaluation method against ten criteria. The first three relate to operations and are (1) procedures for selecting testers or panelists, (2) procedures for training testers or panelists, and (3) procedures for preparing samples. The next five relate to usefulness of application and are (4) detection threshold measurement, (5) establishment of functional relations, (6) operation of a water treatment plant, (7) performance of consumer surveys, and (8) creation of water quality standards. The final two are (9) reliability of data and (10) validity of data. Systematic analysis of the three sensory evaluation methods against the ten criteria shows that all three methods have areas of decided strength and weakness. Future research can overcome weaknes...

Flavor-Profile Analysis: An Objective Sensory Technique for the Identification and Treatment of Off-Flavors in Drinking Water

Flavor-profile analysis (FPA) is a sensory method utilizing a trained panel of four to six individuals. Reference materials are used to establish a common vocabulary for different odors found in drinking water. Known quantities of different taste- and odor-causing chemicals are evaluated to calibrate the panel on a consistent intensity scale. Each identifiable descriptor is assigned its own intensity. This method has been successfully applied in the analysis of musty-smelling compounds, e.g., 2-methylisoborneol (MIB). MIB samples and standards from 1 to 80 ng/l have been shown to observe the WeberFechner law (i.e., a plot of flavor intensity versus logarithm of concentration of MIB yielded a straight line). FPA has also been used to handle fishy/swampy odor problems. In many instances, specific causative organic compounds were not identified; however, FPA evaluations of water using different free-chlorine dosages and contact times made possible immediate resolution of these odor problems. FPA has yielded reproducible sensory data that have been useful in better understanding and handling off-flavors in drinking water.

Development of the Flavor Profile Analysis Method into a Standard Method for Sensory Analysis of Water

The standard methods committee for the 1990 edition of Standard Methods for the Analysis of Water and Wastewater has decided to consider adding a new (provisional) method for the sensory analysis of drinking water - Flavor profile analysis (FPA). A series of issues must be addressed before FPA can become a standard method. The methodology (e.g., temperature of aroma samples, sniffing technique, use of cups vs. flasks, rest intervals between samples, maximum number of samples examined per session) must be standardized. Reference standards for odors must be developed and implemented in order to achieve consistent odor quality descriptions. Development of a flavor wheel can help aid the classification and identification of odors.

Flavor Components and Factors Associated with the Development of Off‐Flavors in Cooked Turkey Rolls

ABSTRACTThe influence of storage and roll position on the development of warmed‐over flavors in cooked turkey rolls was investigated. Following cooking the rolls were refrigerated for 0, 2 and 4 days and analyzed by headspace gas chromatography/mass spectrometry, TBA numbers, flavor profile analysis, and sensory category scaling. TBA numbers increased significantly by 52 and 165% after 4 days in the interior and exterior portions of the rolls, respectively, and were correlated with flavor deteriorations. Thirty‐two compounds were identified, 30 of which are potential products of fatty acid autoxidation. In general, their concentrations were influenced by storage and roll position and correlated to TBA numbers and off‐odor and flavor notes.

Training Panelists for the Flavor Profile Analysis Method

The drinking water industry needs a standard method for determining the aesthetic quality of water. Currently, only sensory analysis provides the necessary information on the flavor and aroma of drinking water. The flavor profile analysis (FPA) method, as conducted at several water utilities, has provided reproducible results on both the intensity and the description of flavor and aroma. After a short training period, a panel can help provide organoleptic information for the water utility manager. The selection and initial training of panelists is an important aspect that must be considered if a panel is to provide reliable information. This article presents a general introduction about panel training in the FPA method.

Interdependency and Underlying Dimensions of Sensory Flavor Characteristics of Selected Foods

Flavor profile data for beefsteaks, fish gels, frankfurters, peanuts, peanut butters, and baked sweet potatoes were subjected to principal component analysis to study the interdependency and the underlying dimensions of the sensory flavor characteristics in order to simplify the method of flavor profile analysis. The character notes used by the panel to describe the flavor profile of each food were not completely independent. The underlying dimensional structure had a number of dimensions equal to approximately 1/3 the number of character notes which explained about 3/4 of the total variance. Flavor profile analysis for each of the evaluated foods could thereby be simplified through reducing the number of character notes to about 1/3 the original number.